Decking On Uneven Concrete Surface

[username132]

Mum's back yard has an uneven concrete surface. The diagram shows lines in the concrete, which aren't cracks, but more like ridges where seperate "lots" (i.e. mixed and layed at seperate times?) of concrete meet. It's been like this ever since we moved in, when the yard was used as a garage. The blue arrow shows the general inclination of the surface, with water running to, and being trapped in, the corner.

The next image attempts to show what we'd like to do with the yard - decking in the middle, with soil for plants around the edge. Would it be possible to lay the decking on this uneven foundation or would it be easier to make the foundation even first? What would be the easiest way to do this?

 

[tomos]

find the highest point on the floor and start your first brick to take the joists for the decking. Once all the bricks are level you can start laying your joists to take the deck boards.

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[Thermo]

We normally make the outer frame first then set it on timber posts resting on the concrete. Once that is levelled and the rest of the frame is built we then put posts where needed under the spans of the joists to stop any bounce.

 

[WabbitPoo]

yep, so much easier to build the frame first then support it level. You're not going to put soil on top of concrete to make the beds, are you?

 

[username132]

find the highest point on the floor and start your first brick to take the joists for the decking. Once all the bricks are level you can start laying your joists to take the deck boards.

I'm not sure I understand - what consistency does that mortar have - are you suggesting that I slap on some concrete, make sure that it's level with the help of bricks and a spirit level and then work from there? If the decking was only supported at the outer edges and not in the middle, wouldn't it be at risk of breaking in the middle?

We normally make the outer frame first then set it on timber posts resting on the concrete. Once that is levelled and the rest of the frame is built we then put posts where needed under the spans of the joists to stop any bounce.

What's a 'timber post' in this context? You're saying I can prop up the decking with chunks of wood in the same manner as you might stop a table from wobbling by putting catalgoues under the short leg or am I misunderstanding?

As for putting soil on top of the concrete, yeah, that's my plan - do you think that there wont be enough drainage?

 

[WabbitPoo]

unless the soil is very deep, no plants will really thrive over concrete.

As regards posts, prop the frame where you want it, level and with a slight run-off in the required direction, then screw 4" wooden posts to it so they sit on the floor. When its all attached, saw off the bits of post sticking up over the frame.

 

[Thermo]

youve got the understanding exactly right, just as wabbitpoo says. trust us we do a lot of it!